1. Field of the Invention
The present invention relates generally to electronic testing assemblies, and more particularly to a multiple contact test probe assembly useful for testing integrated and hybrid electronic circuits.
2. Description of the Prior Art
Recent developments in hybrid and integrated electronic circuits have resulted in progressive miniaturization of these devices. In the manufacture of these circuits, it is necessary to conduct tests to determine the circuits electronic characteristics, in order to discover defective devices prior to or after packaging. Further, it is a common practice of the purchaser of such devices to conduct tests prior to using the equipment in which the devices are installed. This multiple testing demands testing equipment capable of performing these tests at high rates of speed with precision.
With regard to such test equipment, there has been developed test probe cards which generally consist of an insulated printed circuit board having an opening to provide access to an integrated circuit, or electronic circuit positioned adjacent to, or underneath the board. The opening is surrounded by a ring of test probes, each of which is bound to the circuit board and each of which has a probe for making contact to a pre-determined contact pad on the circuit under test. Examples of such prior art arrangements are disclosed in the following United States patents: U.S. Pat. Nos. 3,560,907 to Heller; 3,866,119 to Ardezzone.
In the past, it has been the custom to use point-type needle contacts to make electrical contacts for testing purposes. Frequently, the distance between each corresponding probe arm and the extremity of the conductive tip differs; as a result, some of the tips will "dig" into the corresponding conductive pad on the electronic circuit, while other tips may not make sufficient electrical contact at all. It is, therefore, desirable to provide some means for adjusting for slight changes in the distance between the end of the conductive tip and the metallic pad to be contacted by the tip on the circuit under test, and to further provide some flexure in the tip so as to prevent destruction of the metallic contact pad.
Another difficulty experienced with the testing of electronic circuits of this type is the buildup of a surface oxide coating on the metallic contact pads located on the device being tested. Unless these surface oxide coatings are removed, a correct electrical connection by the test probe to the underlying contact pad cannot be made for testing purposes.
In the construction of packages useful in integrated circuit technology, a type of circuit known as a "dual in-line" package has been developed. The "dual in-line" package consists of multiple contacts or leads which extend from a non-conductive material which encases the active circuit element. Dual in-line packages are characterized by the leads being in different planes. It is, therefore, necessary in the testing of such devices to provide means for making contact with the electrical leads of packages in which the leads may be in different planes.